This invention relates to grease filters, and more particularly to a filter which removes airborne grease particles.
A considerable hazard is created by airborne grease particles exiting an exhaust stack. The airborne grease particles are created in abundance from restaurant cooking equipment. If not removed from the air, the grease will collect on the sides of exhaust ducts and the exhaust stack. If this happens a flare up on a grill, range, fryer or other cooking equipment can touch off a serious fire in the grease in the ductwork and stack. Airborne grease in the ductwork can also settle on the ventilating fans and motors for such fans resulting in a reduction in efficiency of the ventilating equipment.
Grease filters are employed at the entrance to the ductwork to alleviate the potential hazards. The filters provide surfaces on which the airborne grease particles will collect and the collected grease will drain away. The air entering the ductwork thereby has at least the heavy greases removed from it. One form of grease filter now in use consists of a series of layers of an expanded metal media some of which are corrugated. The air is forced to follow a tortuous path and in so doing the suspended grease particles attach themselves to the surfaces of layers of expanded metal. Such form of grease filter does an effective job of removing grease particles from the air but does less well in retarding a flame from shooting through the filter from the grill below. Another form of filter in use is fabricated from two layers of semicircular cylindrical baffles which are arranged in alternate directions so that the air does not have a direct path through the filter. This baffle filter has the semicircular cylindrical baffles arranged vertically and the grease which collects on their surfaces drains down to the bottom of the filter where it exists through drain holes and is collected in a trough for removal. This latter form of filter is particularly useful for preventing a flame from passing beyond a certain point into the ductwork beyond the filter. Because its surface area is limited, it functions less well to remove the airborne grease.
Any such grease filter must present a relatively low static pressure across its thickness so as to minimize the size of the blowers needed to evacuate the ductwork and therefore to minimize the energy consumed. Such filters should also be cleanable so that they can be reused.
By my invention I provide a simple and relatively inexpensive grease filter which functions to effectively remove the airborne grease and also to retard flames from shooting through the filter.